This invention relates to a novel gasket having significant heat-insulating properties.
While the gasket can be used in many environments, one which gave rise to a serious problem solved by this invention, will serve as an example. This is the gasket used in automobile engines between the carburetor and the manifold, in other words, the gasket used between the carburetor and the engine casting, to which the carburetor is mounted by bolts. Heretofore, a fiber gasket about 1/32nd to 1/16th inch thick or a metal inserted asbestos gasket has been used, its function being to seal, so that the fuel -- gasoline, gasoline vapor, and mixture of gasoline and air -- could not escape to the atmosphere through this connection, nor could air from the atmosphere be drawn in through the connection. Such fiber gaskets were able to provide little thermal insulation. This factor was given little consideration until recently, but now it is recognized that such insulation is necessary to reduce fuel bowl temperatures, and it was found that problems were being caused by the passage of heat from the engine manifold at the engine casting to the carburetor, and that this heat transfer was affecting the operation of the carburetor by raising the temperature of the fuel bowl to an excessive temperature.
The initial attempt to solve this problem comprised using thicker gaskets, frequently about one-fourth inch thick, sometimes even thicker, in an attempt to provide some thermal insulation. However, this had difficulties too in achieving accurate control of thickness and other dimensions which are necessary for good sealing performance, and for uniform distribution of compressive loads over the entire flange surface.
Other attempts combined in laminar form resin-impregnated vegetable fiberboard and elastomeric sheets.
As indicated above, it is important to provide a gasket having better heat-insulation properties. It is also important to provide a more uniform distribution of the compressive loads over the entire surface of the flange. It has also been important to provide more accurate control of the thickness and other dimensions which contribute to sealing performance. Also, there have been problems in taking care of various three-dimensional configurations, because the gaskets have heretofore been cut from a sheet of constant thickness; while this has been a generally economical method for making gaskets, it gave no three-dimensional control or configuration at all.